Answer:
a) Heterogeneous mixture (b) Homogenous mixture (c) Pure substance (d) Pure substance
Explanation:
Homogenous mixtures contains mixture of substances with similar proportions while Heterogenous mixture contains substances with a varying proportion.
Answer:

Explanation:
We already know that the mass number of an atom is the sum of the number of protons and the number of neutrons.
So, the mass number of this isotope is;
Number of protons = 7
Number of neutrons = 8
Mass number = 7 + 8 = 15
Hence, the isotope is;

Answer: 1. Is2 2s2 2p3
2. Nitrogen
Explanation: The number of electron present In C = 6
But an extra electron is added since the charge on C is -1, this therefore makes the total electron 7.
1. By arrangement, the Electronic configuration is therefore;
Ans: 1s2 2s2 2p3
2. It is explained how C has 7 electrons, we can proceed then.
Neutral atom have atomic number of 7.
The element with atomic number of 7 is;
Ans: NITROGEN